Engine control modules (ECMs) for powertrain applications generally include controllers, such as the MY 2008 MT40 series controllers provided by Delphi Automotive Systems. These controllers have applications on various vehicles made by several different manufacturers. For example, CAM phasor outputs are generally driven by such controllers to improve idle smoothness and obtain improved power curves at high speeds. Some of these applications require driver circuits that function as low-side drivers, while other applications require high-side drivers.
As low-side drivers are generally less expensive than high-side drivers, most vehicle manufacturers require low-side drivers. Other manufacturers, however, specify high-side drivers because they believe the increased cost is justified by the desire to avoid undesirable effects of shorts to ground (which may be more likely and prevalent than shorts to battery) and to remove power from the load during a short to ground. Unfortunately, not only are conventional high-side drivers, such as the miniPROFET® BSP 452 by Infineon Technologies, generally more expensive, but they also occupy limited printed circuit board (“PCB”) space, increase complexity and component count, and typically require additional microprocessor resources (normally quite limited in such applications) for drive and fault diagnostics. Moreover, as relatively few applications specify high-side drivers, the cost of implementing a high-side driver would become carrying cost for the remaining controllers. This is undesirable as such controllers are frequently used in cost-sensitive applications.
Additionally, conventional high-side drivers do not facilitate fault detection as efficiently as low-side drivers. Off-the-shelf high-side driver ICs current limit their outputs during a short circuit event, and remain powered a relatively long period of time (typically approximately 200 microseconds) or in some cases until the junction temperature exceeds a shut-off threshold. This thermal shut-off approach may require heat sinking or heat removal measures. These short circuit event operating conditions are stressful and may degrade the performance and/or operating life of the device.